Sample size reduction device



May 19, 1970 w. M. BROMAN, JR 3,512,418

SAMPLE SIZE REDUCTION DEVICE Filed Sept. 27, 1968 flA/QT/CZE F550ATTORNEYS United States Patent 3,512,418 SAMPLE SIZE REDUCTION DEVICEWarren M. Broman, Jr., Tulsa, Okla., assignor to Atlantic RichfieldCompany, a corporation of Pennsylvania Filed Sept. 27, 1968, Ser. No.763,319

Int. Cl. G01n 1/20 US. Cl. 73-422 Claims ABSTRACT OF THE DISCLOSURE Aparticulate sample is removed from a feed pipe carrying the sample byhaving a plurality of concentric pipes of varying diameters positionedwithin the feed pipe one above the other so that the sample in the feedpipe flows through successively decreasing diameters. The volume of theparticulate sample is reduced while maintaining particle sizedistribution by placing a plurality of bars within the pipes to mix thesample. An extraction pipe of smaller diameter than the last concentricpipe and connected to the last concentric pipe leads to an externalcollection point where the particulate sample is removed.

The present invention is directed to a method of reducing the volume ofa sample of fluidized particles while maintaining normal particle sizedistribution. Specifically the invention relates to the use of pluralconcentric pipes and bars placed within the pipes perpendicular to theflow of the solids.

In taking samples of crushed materials or other particulate matter(e.g., ores, oil bearing shale, catalysts, etc.) size segregation oftenoccurs causing the sample to be non-representative. A non representativesample will often result in incorrect analyses and cause errors in plantoperations. The present invention avoids this problem by effectivelyremixing and redistributing the particles after each reduction in samplevolume.

The apparatus of the present invention is particularly useful in oilshale retorting where particle size distribution is of particularsignificance. Fines in a retort feed, for example, cause a decrease inyield and bogging of the oil recovery system by being blown out of theretort with the product gases. It is possible for fines to cause retortoperability problems such as uneven burning, and can even extinguish theflame in the combustion zone. Moreover large shale particles will not beefiiciently retorted, and thus a loss in yields will occur. The retortconditions in oil shale processes can be varied to alleviate suchproblems, but this requires knowledge of the particle size distributionof the oil shale being fed the retort. The present invention providessuch knowledge easily and inexpensively and thus provides for moreetficient use of oil shale.

While the apparatus of this invention is particularly adapted for use inoil shale retort processes it may be employed in any instance whereknowledge of particle size distribution of a particulate stream isdesired.

Generally, the material to be sampled flows into a pipe and across aseries of bars that prevent it from flowing in a straight line thuseffectively mixing the sample. From this point, part of the samplepasses inside a sec ond, smaller, concentric pipe and is again mixed bymore bars and passed on to a further, even smaller sample volumereducing pipe. Finally, the sample passes out of the main line andthrough a sample line which generally is smal er than the last samplereducing pipe. In gen eral, since the material at the outer edges of thepipe may not be adequately mixed, the sample reducing pipes are madesuccessively and gradually smaller as the sample passes through thesystem to insure that a true sample is 3,512,418 Patented May 19, 1970taken. Reductions of from about 2 or 5 to 50% in the cross-sectionalarea of the pipe can be generally used with the reduction in areabetween adjacent stages decreasing as the number of stages increases.The number of stages can vary and depends upon the volume of sampledesired and the characteristics of the material to be sampled, althoughat least three stages are preferred.

Referring to the drawings, FIG. 1 is a section of the preferredembodiment of the invention showing the main line, the plural concentricpipes, the sample outlet pipe and the mixing bars.

FIG. 2 is a top view of the pipe showing the preferred method ofattaching the concentric pipes to the inside of the main pipe.

FIG. 3 is a section of the preferred embodiment of the invention showingthe main line, the plural concentric pipes, the sample outlet tube andthe mixing bars opposed perpendicularly in adjacent mixing areas.

Specifically, the sample material enters the feed pipe at point 11 andpasses over mixing bars 12 where the random particle distribution isassured. Part of the sample passes into concentric pipe 13 and the restis rejected and flows down the area outside the smaller pipes.

The sample within concentric pipe 13 is remixed by another group of bars12 and a portion of it passes on to the next concentric pipe 14 where itis again remixed, while the remainder passes out of the system throughpipes 16 and 17.

As shown in FIG. 3, the mixing bars 12 in adjacent mixing areas may beopposed perpendicularly to each other.

The sample in concentric pipe 14 is .further reduced in volume beforeentering and being remixed in concentric pipe 15, from which part of thesample passes into sample line 18 and can be collected for testing.

FIG. 2 shows the support for the top concentric pipe which is effectedby plural braces 19 between the concentrio pipe 13 and the feed pipe 17.There are three braces in the preferred embodiment but it is to beunderstood that any means that will support the concentric pipes and besufficient to make the present invention operable will be acceptable.

To illustrate the invention, about 30,000 lbs. of oil shale were fedinto a sampler, as the one shown in the drawing, over a four-day periodwith about 260 lbs. [being taken out of the sample line during thisperiod. The table compares (feed material and sample material) screensize required to pass a given percentage of the feed and samplematerials, and shows a close correlation between the sample material andthe feed material particle sizes.

TABLE Screen size (inches) Percent of material passing Feed materialSample material It is claimed:

1. An apparatus for reducing the volume of a particulate sample whilemaintaining particle size distribution, said apparatus comprising a feedpipe carrying the sample, a plurality of concentric pipes of varyingdiameters, positioned within the feed pipe one above the others so thatthe sample in said feed pipe flows through successively decreasingdiameter, concentrically arranged pipes, means for mixing the portion ofsaid particulate sample passing through at least the first of theconcentrically arranged pipes and sample extraction means arrangedbeneath the last of the concentrically arranged pipes for removing to anexternal collection point a portion of the particulate sample which hasthe particle size distribution of the sample.

2. The apparatus of claim 1 wherein there are at least threeconcentrically arranged pipes.

3. The apparatus of claim 1 wherein there are mixing means in each ofthe concentrically arranged pipes.

4. The apparatus of claim 1 wherein the mixing means comprises aplurality of bars positioned within the first of said concentricallyarranged pipes.

5. The apparatus of claim 6 wherein said bars are opposedperpendicularly in adjacent mixing areas.

6. The apparatus of claim 4 wherein there are mixing means in each ofsaid concentrically arranged pipes.

7. The apparatus of claim 6 wherein there are at least threeconcentrically arranged pipes.

8. The apparatus of claim 1 wherein said extraction means is anextraction pipe forming a continuation of the last concentricallyarranged pipe.

9. The apparatus of claim 8 wherein the extraction pipe is concentricwith and smaller than said last concentrically arranged pipe.

10. The apparatus of claim 1 wherein each succeeding concentricallyarranged pipe in the line of flow of the sample has from about 2 to 50%less cross-sectional area than the immediately preceeding concentricallyarranged pipe.

References Cited UNITED STATES PATENTS 1,559,155 10/1925 Bullock 732112,322,018 6/1943 Huber 73442 XR 2,452,224 10/ 1948 Collett 73-4215 S.CLEMENT SWISHER, Primary Examiner C. POST III, Assistant Examiner

